Eight out of twelve species of sea turtle are on the endangered species list. A large part of the problem is that the hatchlings crawl toward lights along the beach instead of toward the moonlight reflecting off of the water and are killed. Lights may also discourage female turtles from coming ashore to nest.
Turtle nesting season runs from March 1 to November 1. Florida has mandated that beachfront illumination must be turned off or blacked out during this period. This presents a potential hazard for pedestrians negotiating dark walkways. There is gathering evidence that turtles cannot see red and/or yellow wavelengths well. The present application uses LEDs of such peak wavelengths, preferably red LEDs, as Turtle Friendly Lights. In an implementation, a light also may use an incandescent or fluorescent white light and red LEDs with the same power source switchable between emitting white light and red light.
Due to the nature of color vision, monochromatic red light may be used. Filtered (incandescent) white lights may look red to humans while still emitting a significant portion of yellow, green and even blue light. These shorter wavelengths of light do not significantly impact the perception of red color to humans, but may still be visible to turtles.
Low-pressure sodium vapor lamps emit nearly monochromatic yellow light that has been shown not to interfere with the nesting behavior of some species of turtles. This color may be unappealing and can exhibit poor color rendering properties. Due to their size, power supply requirements and expense, it is difficult to integrate these lamps with another more traditional light source to provide flexible and appropriate landscape and decorative lighting. The low-pressure sodium lamps are more suited to area illumination of parking lots and highway interchanges.
Traditional landscape lighting uses incandescent or fluorescent lighting fixtures. Both of these light sources emit significant amounts of light at wavelengths less than 570 nm, which has proven to be disorienting to both nesting adult turtles and hatchlings. While these light sources could be rendered more ecologically compatible in turtle nesting areas by use of filters, significant labor is required to install and uninstall these filters at the beginning and end of turtle nesting season. Further, high quality filters that block all light emission at wavelengths below 570 nm and will not degrade in the temperatures and humidity typical of turtle nesting beaches are expensive and are not available in useful shapes. Therefore, filtering will be an expensive and inconvenient solution.